Vehicle restraints are commonly employed to prevent a truck from pulling away from a loading dock during a loading operation. A conventional vehicle restraint is mounted on the front face of the loading dock and includes a hook-like restraining member that is movable between a lower storage position and an upper operative position, where the restraining member engages the ICC bar at the rear end of the truck to prevent movement of the truck away from the dock. The ICC bar is a horizontal bar located at the rear of the truck beneath the truck bed, and is designed to prevent a vehicle from underriding the truck in the event of a rear end collision.
Certain types of vehicle restraints are moved manually by an operator from the lower storage position to the upper operative position, while in other types of vehicle restraints the hook or restraining member is power driven to the upper operative position and is either power driven downwardly to the storage position or is arranged to fall by gravity to the storage position.
While the most common types of vehicle restraints employ a hook-like member that is moved from a lower storage position to an upper operative position, vehicles restraints are also known which utilize a downwardly facing hook that is moved downwardly to the operative position. In this latter type the downwardly facing hook is secured to the upper end of a cylindrical rod and the rod is mounted for sliding movement between a pair of spaced guides mounted on the front face of the dock. For storage, the rod is rotated to pivot the hook to a position located generally parallel to the front face of the dock and the hook is retained in the upper storage position by engagement with the upper edge of the one of the guide tracks.
To move the hook to the operative position, the hook is pivoted 90.degree. so that it extends outwardly from the dock and it is then permitted to fall by gravity between the spaced guide tracks into engagement with the ICC bar.
A vehicle restraint having a downwardly facing hook has the advantage that it is able to follow upward and downward float or movement of the truck bed during a loading operation without the need of biasing means.
However, it has been found that in certain situations where cargo is loaded on the truck bed, the truck bed may descend to a position where the hook cannot be moved upwardly and pivoted to its storage position, with the result that the hook cannot be released.